Sweetening sour hydrocarbon distillates and sweetening agents therefor



Uni ed states P tc Q Carl Robert Bauer,,Elkton, assignor to E. I. do Pout de Nemours and Company, Wilmington, Del., a corporation of Delaware No Drawing. Filed Aug. 24, 1959, set. No. 835,433-

' 20 Claims. 01. 208-207) V This invention relates to a novel process for sweetening sour hydrocarbon distillates, particularly for accelerating the sweetening obtained by the use of phenylene diamine sweetening agents, and to new compositions of matter which are'particularly adapted for use in such process. I I

Sour hydrocarbon distillates are petroleum products which contain objectionable amounts of sulfhydryl compounds, mainly organic mercaptans. The treatment of such distillates, to decrease the mercaptan content thereof to an inoffensive low level called sweet, is known as a sweetening process. Many sweetening processes are known to the art. One common and widely employed sweetening process is the antioxidant or inhibitor sweetening process which comprises contactingthe sour hydrocarbon distillate with aphenylene diamine oxidation inhibitorin the presence of oxygen and usually in conjunction with a separate phase of an aqueous alkaline solution. Such process was first disclosed by Devol and Ayers in Patent 2,508,817. Considerable research has been carried out in an attempt to improve such process and to accelerate the rate at which the desired sweetening is accomplished. i To the refiner of hydrocarbon products, it is important to eifect sweetening in as short a time as possible, because of the need to meet production and shipping schedules. With storage space-usually short, it is generally desirable to accomplish'sweete'ning on overnight storage or within 24 hours. Another reason for accelerating sweetening is that with gasolines for example that are inclined to be unstable, slow antioxidant sweetening may promote instability, for in general the longer the time to sweeten, the higher the final peroxide content (which can lead to gum formation). The rate of sweetening however is often unpredictable, even with stocks of quite similar. composition and prior processing history. Whereas one may sweeten readily, another may be slow to sweeten or not at all sweetened in a reasonable time.

It is an object of this invention to provide an improved process for sweetening sour hydrocarbon distillates. Another object is to provide a process for decreasing the mercaptan content of sour hydrocarbon distillates by means of a novel sweetening agent which is at least as etfective as the phenylene diamine sweetening agents.

A particular object is to materially improve the sweetening of sour hydrocarbon distillates with phenylene diamine sweetening agents by employing in conjunction therewith a novel agent which greatly accelerates the sweetening process and which renders the process particularly eflfective for sweetening those sour hydrocarbon distillates that are difficult to sweeten or not sweetened by the conventional phenylene diamine sweetening processes. A further object is to provide novel compositions of mat- 'ter which aremixtures of a phenylene diamine and a guanidine and which are particularly effective for use in the antioxidant sweetening process. Another object is to advance the art. Still other objects will appear hereinafter. l i

2,983,674 Patented ,May 9, test The above and other objects are accomplished by this invention which comprises the process for decreasing the mercaptan content of a sour hydrocarbon distillate which comprises contacting saiddistillate in the presence of oxygen with from about 0.5 to about 50 pounds per 1000 barrels of distillate of a member of the group consisting of a guanidine and the combination of 0.1 to about parts by weight of a guanidine and 99.9 to about 10 parts by weight of aphenylene diamine sweetening agent, said guanidine being-amember of the group consisting of guanidine and substituted guanidines in which the substituents consist of 1 to 5 members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which the oxygen atoms are ether oxygens, and .azahydrocarbon radicals in which the nitrogen atoms are tertiary amine. nitrogens, each of said substituentscontaining lto .18 carbon atoms; and further comprises novel compositions which are particularly adapted for use assweetening agents for sour hydrocarbon distillates which compositions consist essentially of a mixture of 99.9 to about 10 parts by weight of a phenylene diaminewhich is a sweetening agent for sour hydrocarbon'distillates and 0.1 to about 90 parts 'by weight of a guanidine of the group consisting of guanidine and substituted guanidines'in which the substituents consist of l to 5 members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which the oxygens atoms are ether oxygens and azahydrocarbon radicals in which thenitrogen atoms are tertiary amino nitrogens, each of said substituents containing 1 to 18 carbon atoms. f

It has been found that the mixtures of phenylene di-' amine sweetening agents and guanidines which constitute the novel compositions of this invention are homogeneous, normally liquid mixtures which are particularly effective for use in sweetening sour hydrocarbon distil lates in the conventional phenylene diamine antioxidant sweetening process. The guanidine improves the visual appearance of the diamine, producing a mixture which is clear and bright and inhibits deterioration of the phen ylene diamine, retarding the darkening thereof.

. It' has been further found that the guanidines of this invention may be used alone as the sweetening agent in place of the phenylene diamine sweetening agents in the conventional antioxidant sweetening processes. When so used, the guanidines of this invention appear to be at least as effective as thephenylene diamine sweetening agents and in many cases are superior thereto.

Preferably, however, the guanidines of this invention are employed with the phenylene diamine sweetening agents and in the conventional antioxidant sweeting process. The combination of a guanidine and a phenylene diamine sweetening agent appears to be more efiective synergistically than either alone, greatly increases the rate at which the mercapstan content of the sour hydrocarbon distillates is decreased, and is particularly effective to reduce the mercaptan content of sour hydrocarbon distillates that normally, in containing significant proportions of tertiary alkyl mercaptans, respond rather poorly to treatment with the phenylene diamine sweetening agents alone. Such guanidines have no deleterious effect on gasoline quality as measured for example by the induction period tests of ASTM D525 or by the F. storage gum test evaluated by ASTM D381. Furthermore, the use of such combination has the further advantage over the use of the phenyl: ene diamine sweetening agent alone in that the treated distillates have improved color stability, i.e. with respect to color development on exposure to actinic light. 4

The guanidines that may be used in this invention include guanidine itself and the substituted guanidines in which the substituentsconsist of 1 to,5 members of wherein R through R may be hydrogen or a substituent as above described and preferably at least one of R to R will be such a substituent. In these guanidines, all three positions (referring to the Ns in the formula) are essentially equivalent, as it is immaterial whether a substituent is on the doubly bonded N or on a singly bonded N. The hydrocarbon substituents may be saturated or unsaturated acyclic, alicyclic, or aromatic hydrocarbon radicals, such as alkyl, alkenyl, cycloalkyl, aryl, alkaryl, aralkyl, and combinations thereof. Thus, they may be methyl, ethyl, butyl, butenyl, octyl, hexyl, decyl, dodecyl, hexodecyl, octadecyl, octadecenyl, octadienyl, cyclohexyl, phenyl, tolyl, phenylethyl, and ethylphenyl radicals, which may be the same or different.

When the substituents are oxahydrocarbon radicals, the ether oxygens may be members of open chain or cyclic radicals Such radicals may be aliphatic, cycloaliphatic or aromatic radicals which, except for their ether oxygens are hydrocarbon radicals. Representative oxahydrocarbon radicals are: 2-methoxyethyl-, 3-ethoxypropyl-, 2-oleylethy1-,'4-butoxybutyl-, m-methoxyphenyl-, p-nonyl- OXYPhEHYI, and Z-(p-methoxyphenyl) ethyl-radicals.

When the substituent is an azahydrocarbon radical, the tertiary amino nitrogen may be a member of an open chain or a cyclic radical, and these radicals may be aliphatic, cycloaliphatic or aromatic radicals which, except for the tertiary amino nitrogens, are hydrocarbon radicals. Representative azahydrocarbon radicals are: 3- dimethy1aminopropyl-, 3-dibutylaminopropyl-, 3-(N-methyloctadecylamino)-propyl-, 2-diethylaminoethyl-, 2-di propylarninoethyl-, p-dimethylarninophenyl-, m-diethylaminotolyl-, 3-piperidinopropyl-, and Z-piperidinoethylradicals. Also, both the ether oxygens and the tertiary amino nitrogens may be present at the same time, either in separate radicals as above exemplified or in the same radical as in 2-morpholinoethyl-, 3-morpholinopropyl-, and p-morpholinophenylradicals.

Representative guanidines of this invention are guanidine 1,1-diethyl guanidine 1,3-diethyl guanidine 1,3-di-n-butyl guanidine 1,3-diisopropyl guanidine 1,3-dioctyl guanidine 1,3-dicyclohexyl guanidine l,3-dicyclohexyl-2-n-butyl guanidine 1,1,3-trimethyl guanidine 1,1,3,3-tetramethyl guanidine Pentamethylguanidine 1,l,3,3-tetra-sec. butyl guanidine Phenyl guanidine l-phenyl-l-ethyl guanidine 1,3-di-orthotolyl guanidine 1,3-di-.C C alkyl guanidine, where C -C1g alkyl stands for the hydrocarbon residue from cocoamine 1,2,3-dioctadecyl n-butyl guanidine l ,2,3-dicyclohexyl- 2-methoxyethyl guanidine 1,2,3 -dioctadecyl-(Z-ethoxyethyl)guanidine 1,2,3-dibutyl-(4-butoxybutyl)guanidine 1,2,3 -dicyclohexyl- (p-dimethylaminophenyl) guanidine 1,2,3-dimethyl-( 3-dimethylaminopropyl) guanidine 1,2,3-dicyclohexyl-(3-morpholinopropy1) guanidine It will also be understood that the substituents whether hydrocarbon, oxahydrocarbon or azahydrocarbon, may be polyvalent radicals, as in the case of bis-guanidines which may be prepared by reacting, for example, a carbodiimide with a diamine such as hexamethylenediamine, Buff-diaminoethylether and di-(fi-aminoethyl) amine, as well as in guanidines in which two nitrogens in the same molecule are joined, for example, by the trimethylene radical to form with the central carbon atom a heterocyclic ring. No inoperable guanidine has been found and there does not appear to be any reason to doubt that any guanidine, capable of existing as such, will be inoperable.

The guanidines of this invention are, in general, known to the art. The guanidines may be prepared by any of the processes known to the art. For example, where all the substituents are the same hydrocarbon or oxahydrocarbon radicals, they may be made by reactingthe appropriate amine with cyanogen chloride, e.g. the reaction of cocoamine with cyanogen chloride yields the 1,3- di-C -C alkyl guanidine. When the substituents are ditferent, the guanidines may be prepared by reacting a carbodiimide with an appropriate amino compound, e.g. dicyclohexylcarbodiimide reacts with 2-methoxyethylamine and with 3-dimethylaminopropylamine to yield l,2,3-dicyclohexyl-(Z-methoxyethyl)guanidine, and 1,2,3- dicyclohexyl-(3-dimethylaminopropy1)guanidine, and dioctadccyl carbodiimide reacts with n-butyl amine to produce 1,2,3-di0ctadecyl-n-butyl guanidine.

The phenylene diamine sweetening agents, which may be employed in this invention, are those which are known to the art as useful in the antioxidant sweetening process, such as p-phenylene diamine, the alkyl substituted p-phenylene diamines, and particularly the N,N'-dialkylp-phenylene diamines in which each alkyl group contains from 1 to 12 carbon atoms. Especially preferred is the commercially available and widely used sweetening agent, N,N'-di-sec. butyl-p-phenylene diamine. Other representative phenylene diamine sweetening agents are:

N,N-diisopropyl-p-phenylene diamine N,N'-di-sec. amyl-p-phenylene diamine N,N-di-sec. hexyl-p-phenylene diamine N-ethyl-N-isopropyl-p-phenylene diamine N-isopropyl-N'eec. amyl-p-phenylene diamine N,N'-di-3 (S-methylheptyl) -p-phenylene diamine N,N'-dicyclohexyl-p-phenylene diamine N-isopropyl-N'-sec. butyl-p-phenylene diamine and N-phenyl-N-sec. butyl-p-phenylene diamine The novel compositions of this invention, which are particularly adapted for use as sweetening agents in the process of this invention, are the homogeneous, normally liquid mixtures of guanidines and phenylene diamine sweetening agents. In such mixtures, the proportions of the guanidine and of the phenylene diamine may vary widely, with the guanidine constituting either the major or the minor component. The guanidine may constitute from about 0.1 to about of the mixture with the phenylene diamine constituting 99.9 to-about 10% by weight. Usually, however, the guanidine will account for from about l to about 5.0% and the phenylene diamine from about 99 to about 50% of the composition. The preferred compositions are mixtures of N,N'-di-sec. butyl-p-phenylene diamine and either 1,1,3-trimethylguanidine or 1,1,3,3-tetramethylguanidine, preferably, those in which the guanidine constitutes from about 2% by weight to about 50% by weight, particularly around 10% by weight, of the mixture.

The guanidines and the phenylene diamincs are miscible in each other and hence the compositions are easily formulated, simply by adding one component to the other "mixing to produce a homogeneous blend. ,Repre sentative compositions are tabulated below:

N,N'-di-seo. butyl- 1,1,3,3-tetratnethylp-phenylene guanidine parts diamine. parts by weight by weight it will be advantageous to employ the combination of guanidine and phenylene diamine sweetening agent as a single-package sweetening agent. This may be a mixture of the pure ingredients as such or a concentrated solution thereof in a suitable inert organic solvent such as benzene, toluene, kerosene, ethyl alcohol, isopropyl alcohol, acetone, methyl ethyl ketone and the like.

It is not necessary that the guanidine and the phenylene diamine sweetening agent be mixed prior to their use as the treating agents for the sour hydrocarbon distillate, but each of them may be separately added in the course of the sweetening procedure The guanidine may be added at any step of the sweetening process, simultaneously with, before, or after the addition of the phen ylene diamine sweetening agent. Furthermore, the guanidine may be added either to the hydrocarbon phase or to the aqueous phase that is normally present in the antioxidant sweetening process.

The sour hydrocarbon distillates, which may be treated by the process of this invention, are in general those which are known to the art as being susceptible to antioxidant sweetening. Usually, they will boil in the range of from about 50 F. to about 750 F. They include the petroleum hydrocarbon fractions such as the naphthas, light and heavy raw gasoline fractions, raw kerosenes, diesel fuels, jet fuels, e.g. JP-4 and JP-S kerosene base jet fuels, stove oils, furnace oils, and light gas oil fractions, particularly those containing cracked or olefinic fractions. The agents and process of this invention are particularly applicable to the treatment of the sour hydrocarbon distillates which boil in the gasoline range (from about 80 F. to about 430 F.) and contain cracked or olefinic fractions. Examples are refinery blending stocks and gasolines such as the catalytically and thermally cracked stocks, polymer gasolines, and blends thereof. Straight-run distillates, which are notoriously slow to sweeten, and others which may be slow to sweeten because of their low olefin content, may be blended with cracked or olefinic stocks to render them more susceptible to antioxidant sweetening, as is known in the art. For example, substantial improvements may be achieved in the sweetening rate of such stocks by employing 1 vol. percent or more of olefinic hydrocarbons as blending components therefor.

Before being subjected to the sweetening process of this invention, the hydrocarbon charge may be pro-washed with caustic, as practiced in the art, to eliminate hydrogen sulfide and'some of the mercaptan content. The prewashing treatment may include blowing with air. Such treatment alone is generally insuflficient to sweeten the stock which may still contain a sour mercaptan sulfur content ranging from about 0.001 to about 0.04 g./ 100 m1. of hydrocarbon. Furthermore, since tertiary'and secondary mercaptans are more difiicult to extract with alkali and to oxidize to innocuous products than are the primary mercaptans, the caustic treated stocks may still contain significant proportions of tertiary and secondary mercaptans. It has been found that hydrocarbon stocks that contain souring quantities of tertiary mercaptans in particular are highly resistant to sweetening by the conventionalantioxidant sweetening process. On the other hand, the combinations of phenylene di'amines and guanidines of this invention are very effective to reduce the mercaptan sulfur content of such stocks.

The quantity of the sweetening agent employed for sweetening sour hydrocarbon distillates will vary depending upon the distillate, its source, its composition and prior processing history, and on the degree of sweetening desired. When a guanidine is employed alone, in the absence of the phenylene diamine sweetening agent, it may be employed in a concentration corresponding to the concentration of phenylene diamine employed in the conventional antioxidant sweetening process. Usually, it will be used in a proportion of from about 0.5 to about 50 lbs. per 1000 bbls. of distillate, preferably from about 5 to about 20 lbs. per 1000 bbls.

When both a phenylene diamine sweetening agent and a guanidine are employed in combination for sweetening sour hydrocarbon distillates, the phenylene diamine sweetening agent ordinarily will be employed in the same proportions as it is used in the prior conventional processes for sweetening sour hydrocarbon distillates, that is, in an amount to provide the desired amount of sweetening and to provide the desired antioxidant effect in the distillates, e.g. to inhibit gum formation in the gasolines. Thus, the phenylene diamine sweetening agent normally will be used in a proportion of from about 1 to about 50 lbs. thereof per 1000 bbls. of hydrocarbon, preferably from about 2 to about 20 lbs. per l000'bbls. of distillate. In the presence of the phenylene diamine sweetening agent, the guanidine usually will be employed in a proportion of from about 0.05 to about 10 lbs. per 1000 bbls.

of distillate, preferably from about 0.5 to about 5 lbs. per 1000 bbls. Also, the minimum practical quantity of the phenylene diamine sweetening agent or of the guanidine, is dependent, at least in part, on the quantity, molecular weight, and activity of the other member of the combination. For example, with 1 lb. of phenylene diamine sweetening agent per 1000 bbls. of distillate, it isbetter to employ the larger amount of the guanidine, say 1 to 10 lbs. thereof per 1000 bbls. of distillate. On the other hand, with the larger amounts of phenylene diamine sweetening agent, say from about, 5 to about 20 lbs. thereof per 1000 bbls. of distillate, as lowas 0.1 lb. of guanidine per 1000 bbls. of distillate appears quite satisfactory and as little as 0.01 lb. thereof per 1000 bbls.

of distillate is efiective to significantly decrease the mercaptan sulfur content of the distillate.

The sweetening agent may be used in considerably larger amounts than the maximum amounts above set antioxidant sweetening processes are more particularly described by Devol and Ayers in Patent 2,508,817 and by Rosenwald in Patent 2,616,831.

The guanidines may be employed as such or as salts,-

such as the nitrate, chloride, carbonate and the like. When the salts are used, however, sufficient caustic should be employed to neutralize the acid (nitric, hydrochloric, carbonic) component of the guanidinium salt. For example, the guanidinium salt may be incorporated into the sweetening system by adding it to the aqueous caustic phase normally used in the'sweetening process.

In the preferred process, the sour hydrocarbon distillate fraction to be sweetened is contacted with air, a

. .phenylene diamine sweetening agent, a guanidine of this invention, and an aq-ueousphase immiscible with the by drocarbon. The phenylene diamine, the guanidine, and

the aqueous solution maybe mixed with the hydrocarbon streamtogether or separatelyin any order. The resultant mixture may be passed through any ofthe mixing devices of the art on its way to a storagevessel where the sweet eningis allowed'to "goto completion, The mixture may be further. agitated in the storage vessel before it is allowed to settle. I

The aqueous solutionshouldbe sufficient toform a seption ofadditive corresponding to. about lbs. per 1000 bbls. of the distillate.

EXAMPLE 1 A naturally sour catalytically cracked gasoline containing 0120 vol. percent sulfhydryl sulfur was extracted twice with 5 vol. percent of a 10 weight percent solution of sodium hydroxidein water, thereby. decreasing the .mercaptan sulfur content to 0.0280 g./ 100 ml.

Sweetening test procedurelinch of five 300 ml. portions of the thus treated gasoline, was placed in a one-.

. pint bottle (446 cc. capacity) to which was then added arate "layer on settling, amounting generally to at least 0.01 "vol. percent of the hydrocarbon and, because more and mixtures thereof) and may constitute from about 1 to about 50%, more usuallyabout 5 to about by weight of the solution. While the solvent ordinarily will be water, mixtures of water with hydroxylic media such as the lower alkanols, glycols,, ether alcohols, and. al-

kanolamines, may be used. Also, the aqueous solution 1 may contain a solutizer such as potassium isobutyrate;

or alkylphenols, e.g. :cresofls, or polyhydroxy aromatic compounds, e.g. tannic acid, or petroleum acids, e.g. naphthenic acids may be dissolved in small amounts in the,

alkaline solution.

As iswell known, oxygen must'bepresent. Theoretically, 1 mol. of oxygen is required for every 4 mols. of mercaptan,-' based on the conversion to 'disulfide. In

practice, about'twiceas'much is ordinarily required because of side reactions. It has been estimated that the maximum air required forsweetening is about 75 cu. ft./

1000 bbls. of gasoline at atmospheric temperatures and pressures. Oxygen can besupplied to the system by any means, such as bubbling air, oxygen or any oxygencontaining gas into the composition being treated, or simply by allowing the hydrocarbon to stand in contact with air. Ordinarily, to begin with, there is sutficient air dissolved in the hydrocarbon product. However, if air has to be added, it is usually preferable to add the phenylene diamine first, before introducing the supply of air and to control the amount of air, as given above, to minimize side reactions.

The time required to effect a satisfactory degree of sweetness is generally dependent on the nature and prior treatment of the hydrocarbon distillate, the concentration and nature of the sulfhydryl compounds therein, the quantity of the reagents employed, and on process conditions such as temperature and the mixing means available. sweetening is usually effected between 50 F. and 125 F., preferably from about 70 F. to about 90' R, and, with the usual equipment, may take from minutes to days. However, the use of a guanidine with a phenylene diamine according to this invention results in a marked decrease in the time normally required to reduce the sulfhydryl content of sour hydrocarbon distillates.

In order to more clearly illustrate this invention, preferred modes of carrying the same into eltect, the following examples are given in which the amounts and proportions are by weight except where otherwise specifically indicated. In these examples, the sweetening agent compositions usually were handled as stock solutions in benzene containing 0.84 g. of the composition in 100 ml. of solution, to enable accurate measurements of the amounts employed because of the small quantities thereof involved. The addition of 1 ml. of such solution to 300 ml. of hydrocarbon distillate provides a concentra- 1.0 ml. of a 10 weight percent solution of sodium hydroxide in water and, toprovide the. concentrations tab. ulated below, sufficient quantity of either N,N'-di-sec. butyl-p-phenylene diamine or a mixture of 90 parts by weight of this diamine and 10 parts by weight of; 1,1,33,3- tetramethylguanidine. Each sample was capped, shaken for 15 minutes at room temperature, then stored at 86 F. and analyzedfor its mercaptan sulfur content at the g g 1 times indicated below. I

Guanidine-accelerated antioxidant'sweetening in decreasing the mercaptan sulfur, content of the sour stock. Further, only the samples'containing the guani- Y dine were doctor-sweet at the end of 66 hours.

EXAMPLE 2 1 The sweetening test procedure of Example '1 was repeated on a Gulf Coast catalytically cracked gasoline that was sour to the doctortest and contained0.002l g./ 100 ml. of mercaptan sulfur. The sample of this stock, whichhad been treated to contain 10 lbs/1000 bbls. of the :10 mixture of N,=N'-di-sec. butyl-p-phenylene diamine and 1,1,3,3-tetramethylguanidine, showed, after 19 hours storage at 86 F., a mercaptan sulfur content of 0.0009 g./ m1. and was doctor-sweet. In contrast, the control stock, that had been treated to contain 10 lbs/1000 bbls. of N,N"di-sec. butyl-p-phenylene diamine alone, showed a mercaptan sulfur content of 0.0015 g./100 ml. after 19 hours and was first doctorsweet at 23 hours.

EXAMPLE 3 A catalytically cracked motor gasoline base stock was soured to contain 0.006 g. of mercaptan sulfur per 100 ml. of, solution by blending therein n-butyl mercaptan, isopropyl mercaptan and t-butyl mercaptan, each in quantity providing 0.002 g./ 100 ml. of mercaptan sulfur. The sweetening test procedure of Example 1 was repeated with N,N-di-sec. butyLp-phenyIenc diamine (10 lbs./ 1000 bbls.) and with the 90:10 mixture of N,N'-di-sec. butyl-p-phenylene diamine and 1,1,3,3-tetramethylguanidine (l0 lbs/1000 bbls.). After 18 hours storage at 86 F., the mercaptan sulfur content of stock containing the diamine alone was 0.0026 g./ 100 ml., While that of the'stock containing the diamine-guanidine composition was only 0.0002 g./100 ml., or about that of the control.

Repeating the above experiment with 1,3-di-orthotolylguanidine as the promoter in place of the tetramethylguanidine at the same (1 lb./1000 bbls.) concentration resulted in a mercaptan sulfur content after 18 hours of 0.0014 g./ 100 ml., or about /2 that achieved in its absence.

- N.N-di-sec. 1,1,23,3- Mercaptan Sulfur; g./l00 m1. at-

butyl-ptetramethyl- I phenylene guanidine, i I

diamine, lbs/1,000 bbls. '18 hrs. 42 hrs. 60 hrs. I 1bs.!1,000 bbls. i I

The above data show themarked ettect of the guanidine steam X "H as that of the sample stored in the presenceof 3 had decreased to 0.003 gram per 100 ml.

EXAMPLE 10 Anaturally sour catalytically cracked gasoline, having a mercaptan sulfur content of 0.0094 g./100 ml., was tested under the conditions of Example 1 with 1,3-diorthotolylguanidine as the promoter for N,N'-di-sec. butyl-p-phenylene dial-nine. After 22 hours, the mercaptan sulfur content of acontrol sample stored in the presence of the aqueous caustic alone was 0.0068, that of the sample stored in the additional presence of 10 ':lbs./ 1000 bbls. of the antioxidant had fallen to 0.0024,

and that of the sample containing the guanidine (1 lb./ 1000 bbls.) and the antioxidant (9 lbs./ 1000 bbls.) had decreased to the sweet level of 0.0005.

EXAMPLE "11 The gasoline of Example 4, soured with t-butyl mercaptan to contain 0.006 g. of mercaptan sulfur per 100 -ml., was treated by the procedure of Example 1 with lbs./ 1000 bbls. of 1,2,3-dioctadecyl-n-butyl guanidine (made from dioctadecyl carbodiimide and n-butyl amine and totalling 40 carbon atoms in the substituents) and 9 lbs/1000 bbls. of N,N'-di-sec. butyl-p-phenylene diamine. The amount of this guanidine is equivalent, on a molar basis, to 1 lb./ 1000 bbls. of l,l,3,3-tetraamethylguanidine. After 18 hours, the mercaptan sulfur content of the gasoline was down to 0.0011 g./ 100 ml.

EXAMPLE 12 The soured gasoline of Example 6, having a mercaptan sulfur content of 0.0058 -g./100 ml., was treated by the procedure of Example lwith caustic and lbs./ 1000 bbls. of N,N-di-sec. butyl-p-phenylene diamine and with caustic, 9 lbs/1000 bbls. of N,N'-di-sec. butyl-p-phenylene diamine and 1 lb./ 1000 bbls. of l,2,3-dicyclohexyl(2- methoxyethyDguanidine (made from 2-methoxyethylamine and dicyclohexylcarbodiimide). After 16 hours, the gasoline, which had been treated with .the diamine in the absence of the guanidine, had a mercaptan sulfur content of 0.0052 g./100 ml, while that treated with both the diamine and the guanidine had a rn'er'captan sulfur content of 0.0018 g./ 100 ml.

EXAMPLE 13 A sour kerosene base jet fuel (JP-4), analyzing 0.6% olefins, and a sour furnace oil, containing cracked stocks and analyzing about 4.5% olefins, were each given a 3- minute wash with 10% by volume of 10% aqueous NaOH and the wash liquor discarded. -To samples of each, there was added N,N'-di-sec. butyl-p-phenylene diamine .(diamine) or a mixture (Composition C) consisting of 90 parts by weight of N,N'-di sec. butyl-p-phenylene diamine and 10 parts by weight of 1,-1,3,3-te tra.methylguanidine and the caustic wash repeated, leaving the wash liquor in contact with the hydrocarbon stock. Each sample was then blown with air for 10 minutes and stored at room temperature. The results are given below:

It will be understood that the preceding examples have been given for illustrative purposes solely and that this invention is not limited to the specific embodiments described therein. on the other hand, it will be readily apparent that, subject to the limitations set forth in the general description, many variations can be made in the materials, proportions, conditions and techniques employed without departing from the spirit and scope of this invention. From the preceding description and examples, it will be apparent that this invention provides novel improved processes for decreasing the mercaptan sulfur content of sour hydrocarbon distillates by means of a novel sweetening agent, ,a guanidine, and particularly by novel combinations of sweetening agents, a phenylene diamine sweetening agent and'a guanidine. Particularly, the novel combination of sweetening agents is very effective to provide the desired sweetening in shorter periods of time and is especially nsefulin hard-to-sweeten sour hydrocarbon distillates which contain significant proportions of tertiary mercaptan sulfur. In addition, the guanidines have no deleterious efiect on the quality of the sweetened distillates, but, in the presence of the phenylene diamine, actually improve such quality in certain respects. Also, the new compositions of matter, which are mixtures of the phenylene diarnine sweetening agents and the guanidines, have a better appearance than the phenylene diamine sweetening agents alone and are more stable against deterioration, darkening, and haze formation. Thus, it is apparent that this invention constitutes a valuable contribution to and advance in the art.

The embodiments of this invention in which an exclusive property or privilege is claimed are defined as follows: 1

1. A composition which consists essentially of a mixture of 99.9 to about 10 parts by weight of a phenylene diamine which is a sweetening agent for sour hydrocarbon distillates and 0.1 to about parts by weight of a guanidine of the group consisting of guanidine and substituted guadindines in which the substituents consist of 1 to 5 members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which the oxygen atoms are ether oxygens and azahydrocarbon radicals in which the nitrogen atoms are tertiary amino nitrogens,

each of said ,substi-tuents containing 1 to 18 carbon atoms.

2. A composition which consists essentially of a mix- .ture of 99.9 to about 1.0 parts by weight of an N,N'-di- .alkyl substituted phenylene diamine in which each alkyl group contains 1 to 12 carbon atoms which is a sweeten ing agent for sour hydrocarbon distillates and 0.1 to about 90 parts by weight of aguanidine of the group consisting of guanidine and substituted guanidines in which the sub-v stituents consist of 1 to 5 members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which the oxygen atoms are ether oxygens and azahydrocarbon radicals in which the nitrogen atoms are tartiary amino nitrogens, each of said substituents containing '1 to 18 carbon atoms.

3. A composition which consists essentially of a mixture of 99.9 to about 10 parts by weight of .N,N'-di-sec. butyl-p-phenylene diamine and 0.1 to about 90 parts by weight of a guanidine of the group consisting of guanidine and substituted guanidines in which the substituents consist of 1 to 5 members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which :the oxygen atoms are ether'oxyg'ens and azahydrocarbon radicals in which the nitrogen atoms are tertiary amino :nitrogens, .each of ;said.substituents containing 1 to 18 .carbon atoms.

4. ,A composition which consistscssentially of a mix- .ture of 9.9.9 to about 10 parts by weight of a phenylene .diamine which is .a sweetening agent forsour hydrocarrbon distillates and 0.1 to about90 parts by weight of'a :substituted guanidine in which .the substitnentsacensistiof aesae'ti' 9 7 EXAMPLE 4 A catalytically cracked motor gasoline was soured to contain 0.006 g. of tertiary mercaptan sulfur per 100 ml. by blending therein t-butyl mercaptan in the requisite amount. The sweentening test procedure of Example 1 was repeated with N,N'-di-sec. butyl-p-phenylene diamine and 1,1,3,3-tetramethylguanidine as co-additives in the concentrations and ratios tabulated below. The results follow:

N N-di'sec 1.1.3.3- Mercaptan hutyl-ptetramethyl- Additive Sulfur, phenylene guanidine, Ratio g./100 ml.

diam e, lbs/1,000 bbls. after 19 hrs.

:EXAMPLE 5 Employing the sweentening procedure of Example 1, the gasoline of Example '4,.which had been soured to ,contain 0.0066 gram of mercaptan sulfur as t-butyl mercaptan per 100 ml. of gasoline, was treated with N,N'-disec..butyl-p-phenylene diamine (A.O.), with 1,1,3,3-tetramethylguanidine (TM G), and with mixtures thereof in the proportions indicated below:

Mel-captan Additive S or,

g./100 ml.

after 24 hours Oanstic alone, 1.0 m1./300 ml. gasoline 0. 0058 10 Lbs/1,000 bbls. of A.O.+1.0 ml. caustic 0.0048 10 Lbs/1,000 bbls. of TMG alone (no caustic) 0. 0040 5 Lita/1,000 bbls.-of TM G+0.5 ml. caustic-.- 0.0025 '10 -LbS./1,000 bbls. of mixture of 9 A.0./1 TMG 0. 0000 ,EXAMPLEG.

Tertiary butyl'mercaptan, in quantity to provide 0.0058 g. 'of merca tan sulfurper 100 ml. of solution, was "blended into a catalytic'ally cracked gasoline base stock. .As in the previous examples, 300 ml. portions of the squred stoclt were treated with 1.0 ml. of 10% NaOH and with either 10 lbs/ 1000 bbls. of N,N'-di-sec. butylp-phenylene diamine or a combinationof 9 lbs/ 1000 bbls. *ofthis' diamine and 1 lb./1000bbls. of a guanidine listed "below. The. resulting mixtures were subjected to the results, along with those of the appropriate controls, follow:

. Mercaptan Guanidine l Sulfur,

g./100 ml. after 10 hours None (caustic only 0. 0053 None (caustic an 0. 0051 1 l-diethylguanidi 0. 0034 l-phenyl-lethylgnanidlne. 0. 0025 ,3-di-n-butylguanidin 0. 0022 1,3-diisopropylguan.idine 0. 0013 phenylmmnirlinn O, 0018 1,2,3-dicyclohexyl-n-butylguanidine 0. 0002 1,1,3-trimethylguanldine 0. 0008 Each was added as a benzene solution, except phenyl guanidine which was added as an ethanolic solution.

Significant lowering of the tertiary mercaptan sulfur content of the above described sour gasoline was also obtained on replacing the above guanidines with 1,3-dicyclohexylguanidine, 1 1,1,3,3-tetraethylguanidine, 1,1,3,3-tetrasec. butyl guanidine, 1,3-diethylguanidine, 1,3-dioctylguanidine, or 1,3-di-C -C alkyl guanidine (prepared by reacting cocoamine with cyanogen chloride). 1

EXAMPLE 7 To a sour catalytically cracked gasoline, containing 0.0058 g./10 0 ml. of mercaptan sulfur as t-butyl mercaptan, was added 10% NaOH (1 ml./300 ml. of gasoline) and either 10 or 9 lbs./ 1000 bbls. of N,N-di-sec. butyl-p-phenylene diamine. The samples were handled, stored and analyzed as in Example 1. The sample, that had been treated to. contain 10 lbs./ 1000 bbls. of the diamine, had a mercaptan sulfur content of 0.0056 g./100 ml. after 21 hours and 0.0042 g./ 100 m1. after 45 hours. The sample, containing 9 lbs./1000bbls. of the diamine, also analyzed 0.0056 'g./ 100 ml. of mercaptan sulfur after 21 hours. To the latter sample, 1,1,3,3-tetrametl:ylguanidine was added in an amount corresponding to 1 lb./100 bbls., and the sample stored 24 hours at F., at the end of which time the mercaptan sulfur content was 0.001 g./l00 m1.

EXAMPLE 8 This sample shows that the guanidine promoter of the antioxidant sweentening process may be added as an aqueous solution. To ml. of a water solution containing 10% by weight NaOH was added 0.084 g. of 1,1, 3,3-tetramethylguanidine. By the sweetening procedure of Example 1, 300 ml. samples of a sour catalytically analyzed 0.0010 g./ 100 ml. mercaptan sulfur.

EXAMPLE 9 As in Example 4, a catalytically cracked gasoline stock was soured to contain 0.006 g. of tert. butyl mercaptan sulfur per .100 ml. The test procedure of Example 1 was repeated on 300 ml. samples of the soured gasoline, with N,N'-di-sec. butyl-p-phenylene diamine at a concentration of 10 lbs/1000 bbls. of the gasoline, and with an aqueous phase which consisted of 1.6 ml. water, 1.6 ml. ethyl alcohol and either 0.05 g. sodium hydroxide (A) or 0.07 g. guanidine (B), the amount of guanidine being the molar equivalent of the caustic. After 16 hours, the mercaptan sulfur content of the sample conditions of agitation and storage of Example 1. The $.76 mstoredin the presenceof A was 0.005 g./100 ml. whcreof which contains 1 to 'distillates and 0.1 to about 90 parts by weight of 1,l,3,3-

tetramethyl guanidine.

6. A composition which consists essentially of a mixture of 99.9 to about 10 parts by weight of an N,N-di-- alkyl substituted phenylene diamine in which each alkyl group contains 1 to 12 carbon atoms which is a sweetening agent for sour hydrocarbon distillates and 0.1 to about 90 parts by weight of 1,1,3,3-tctramethyl guanidine.

7. A composition which consists essentially of a mixture of 99.9 to about 10 parts by weight of N,N'-di-sec. butyl-p-phenylene diamine and 0.1 to about 90 parts by weight of l,1,3,3-tetramethyl guanidine.

8. The process for decreasing the mercaptan content of a sour hydrocarbon distillate which comprises contacting said distillate in the presence of oxygen with from about 0.5 to about 50 pounds per 1000 barrels of distillate of a member of the group consisting of a guanidine and the combination of 0.1 to about 90 parts by weight of a guanidine and 99.9 to about 10 parts by weight of a phenylene diamine sweetening agent, said guanidine being a member of the group consisting of guanidine and substituted guanidines in which the substituents consist of 1 to members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which the oxygen atoms are ether oxygens, and azahydrocarbon radicals in which the nitrogen atoms are tertiary amino nitrogens, each of said substituents containing 1 to 18 carbon atoms.

9. The process for decreasing the mercaptan content of a sour hydrocarbon distillate which comprises contacting said distillate in the presence of oxygen with from about 0.5 to about 50 pounds per 1000 barrels of distillate of a member of the group consisting of guanidine and substituted guanidines in which the substituents consist of 1 to 5 members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which the oxygen atoms are ether oxygens, and azahydrocarbon radicals in which the nitrogen atoms are tertiary amino nitrogens, each of said substitutents containing 1 to 18 carbon atoms.

10. The process for decreasing the mercaptan content of a sour hydrocarbon distillate which comprises contacting said distillate in the presence of oxygen with from about 0.5 to about 50 pounds per 1000 barrels of distillate of a substituted guanidine in which the substituents consists of '1 to 5 hydrocarbon radicals of 1 to 18 carbon atoms.

11. The process for decreasing the mercaptan content of a sour hydrocarbon distillate which comprises contacting said distillate in the presence of oxygen with from about 0.5 to about 50 pounds per 1000 barrels of distillate of 1,l,3,3-tetramethyl guanidine.

12. The process for decreasing the mercaptan content 1 of a sour hydrocarbon distillate which comprises contacting said distillate in the presence of oxygen with from about 0.5 to about 50 pounds per 1000 barrels of distillate of the combination of 0.1 to about 90 parts by weight of a guanidine and 99.9 to about parts by weight of a phenylene diamine sweetening agent, said guanidine being a member of the group consisting of guanidine and substituted guanidines in which the substituents consists of 1 to 5 members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which the oxygen atoms are ether Oxygens, and azahydrocarbon radicals in which the nitrogen atoms are tertiary amino nitrogens, each of said substituents containing 1 to 18 carbon atoms.

13. The process for decreasing the mercaptan content of a sour hydrocarbon distillate which comprises contacting said distillate in the presence of oxygen with from about 0.05 to about 10 pounds per 1000 barrels of distillate of a guanidine of the group consisting of guanidine and substituted guanidines in which the'substituents consist of l to 5 members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which-the oxygen atoms are ether oxygens, and

azahydrocarbon radicals in which the nitrogen atoms are tertiary amino nitrogens, each of said substituents containing 1 to 18 carbon atoms, and from about 1 to about 50 pounds per 1000 barrels of distillate of a pheny ene diamine sweetening agent.

14. The process for decreasing the mercaptan content of a sour hydrocarbon distillate which comprises contacting said distillate in the presence of oxygen with from about 0.5 to about 5 pounds per 1000 barrels of distillate of a guanidine of the group consisting of guanidine and substituted guanidines in which the substituents consist of 1 to 5 members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which the oxygen atoms are ether oxygens, and azahydrocarbon radicals in which the nitrogen atoms are tertiary amino nitrogens, each of said substituents containing 1 to 18 carbon atoms and from about 2 to about 20 pounds per 1000 barrels of distillate of a phenylene diamine sweetening agent.

15. The process for decreasing the mercaptan content of a sour hydrocarbon distillate which comprises contacting said distillate in the presence of oxygen with from about 0.05 to about '10 pounds per 1000 barrels of distillate of a guanidine of the group consisting of guanidine and substituted guanidines in which the substituents consist of 1 to 5 members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which the oxygen atoms are ether oxygens, and azahydrocarbon radicals in which the nitrogen atoms are tertiary amino nitrogens, each of said substituents containing l to 18 carbon atoms and from about 1 to about 50 pounds per 1000 barrels of distillate of an N,N- dialkyl substituted phenylene diamine sweetening agent in which each alkyl group contains 1 to 12 carbon atoms. 7

16. The process for decreasing the mercaptan content of a sour hydrocarbon distillate which comprises contacting said distillate in the presence of oxygen with from about 0.5 to about 5 pounds per 1000 barrels of distillate of a guanidine of the group consisting of guanidine and substituted guanidines in which the substituents consist of 1 to 5 members of the group consisting of hydrocarbon radicals, oxahydrocarbon radicals in which the oxygen atoms are ether oxygens, and azahydrocarbon radicals in which the nitrogen atoms are tertiary amino nitrogens, each of said substituents containing 1 to 18 carbon atoms and from about 1 to about 50 pounds per 1000 barrels of distillate of N,N'-di-sec. butyl-p-phenylene diamine.

17. The process for decreasing the mercaptan content of a sour hydrocar on distillate which comprises contacting said distillate in the presence of oxygen with from about 0.05 to about 10 pounds per 1000 barrels of distillate of a substituted guanidine in which the substituents consist of 1 to 5 hydrocarbon radicals of l to 18 carbon atoms and from about 1 to about 50 pounds per 1000 barrels of distillate of a phenylene diamine sweetening agent.

18. The process for decreasing the mercaptan content of a sour hydrocarbon distillate which comprises contacting said distillatein the presence of oxygen with from about 0.05 to about 10 pounds per 1000 barrels of distillate of a substituted guanidine in which the substituents consist of 1 to 5 hydrocarbon radicals of 1 to 18 carbon atoms and from about 1 to about 50 pounds per 1000 barrels of-distillate of an N,N'-dialkyl substituted phenylene diamine sweetening agent in which each alkyl group contains 1 to 12 carbon atoms.

19. The process for decreasing the mercaptan content of a sour hydrocarbon distillate which comprises con- 16 tacting said distillate in the presence of oxygen with from about 0.05 to about 10 pounds per 1000 bzirrels of distillate of 1,1,3,3-tetramethyl guanidine and from about 1 to about 50 pounds per 1000 barrels of distillate of N,N'-

5 di-sec. butyl-pphenylene' diamine.

References Cited in the file of this patent UNITED STATES PATENTS I Rosenwald Mar. 2, 1954 UNITED; STATES PATENT OFFICE @ERT'I'FICATE OF CORRECTION Patent No -2,983,674 V May 9, 1961 I I Carl Roberiz Bauer It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent. should read as "corrected below.

Column 2, line 28, for "oxygens" read oxygen line 56, for "met-capstan" read mercaptan column 3 line 27 for 'fhexodecyln read -\,hexadecyl column 10, line .41 for "100 bbls." read 'lOOO bbls. column l2 line 4L0 for ."guadindines" read guanidines column 13 line 66 for "consists"- read consist column 14, line 44,, for ,5 pounds"v read 10 pounds Signed and sealed this 10th day of October 1961 (SEA L) Attest:

- ERNEST W. SWIDER I l DAVID L. LADD Attesting Officer I Commissioner of Patents USCOMM-DC' UNITED STATES PATENT OFFICE C ERTI-FICATE 0F CORRECTION L Patent No -2,983,674 May 9, 1961 Carl. RobertBauer It is, hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent. should read as corrected below. r

j Column 2, line 28, for "oxygens" read oxygen line 56,

for "mercapstan" read mercaptan column 3, line 27, for

': hexodecyl"- read .hexadecyl column 10, line 41 for "100 bbls. read lOOO bbls. column 12, line 40 for "guadindines" read guanidines column 13, line 66,, for "consists" read consist column 14, line 44, for ,5 pounds" read 10 pounds Signed and sealed this 10th day of October 1961.

' (SEAL) Attest:

ERJ f sT w. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents USCOMM-DC 

8. THE PROCESS FOR DECREASING THE MERCAPTAN CONTENT OF A SOUR HYDROCARBON DISTILLATE WHICH COMPRISES CONTACTING SAID DISTILLATE IN THE PRESENCE OF OXYGEN WITH FROM ABOUT 0.5 TO ABOUT 50 POUNDS PER 1000 BARRELS OF DISTILLATE OF A MEMBER OF THE GROUP CONSISTING OF A GUANIDINE AND THE COMBINATION OF 0.1 TO ABOUT 90 PARTS BY WEIGHT OF A GUANIDINE AND 99.9 TO ABOUT 10 PARTS BY WEIGHT OF A PHENYLENE DIAMINE SWEETENING AGENT, SAID GUANIDINE AND SUBSTIA MEMBER OF THE GROUP CONSISTING OF GUANIDINE AND SUBSTITUTED GUANIDINES IN WHICH THE SUBSTITUENTS CONSIST OF 1 TO 5 MEMBERS OF THE GROUP CONSISTING OF HYDROCARBON RADICALS, OXAHYDROCARBON RADICALS IN WHICH THE OXYGEN ATOMS ARE ETHER OXYGENS, AND AZAHYDROCARBON RADICALS IN WHICH THE NITROGEN ATOMS ARE TERTIARY AMINO NITROGENS, EACH OF SAID SUBSTITUENTS CONTAINING 1 TO 18 CARBON ATOMS. 